Heart failure is a leading cause of mortality in modern society, and is the result from the death of cardiac myocytes. Contractile function of failing hearts can be restored by injecting the heart with embryonic stem cell-derived cardiac myocytes (ESCMs) which integrate into the host tissue. To facilitate production of ESCMs, high throughput screening systems are needed that can quantify ESCM production. The proposed research will develop an instrument that will utilizes live cell and high content screening (HCS) techniques to quantify the occurrence of ESCMs for stem cells cultured in 96-well dishes. The system will record intracellular calcium transients from ESCM cultures, which are a hallmark of differentiated cardiac myocytes. The system will feature electrode and controller assemblies that interface to commercial high content microscopy workstations (e.g., the Beckman IC100 and the Amersham Incell 1000) and will discriminate cells based on expression of fluorescent transgenes. Staining reagents and software for automated image analysis will also be developed to quantify the cellular expression and organization of cardiac-specific structures (myofibrils) and proteins (SERCA2). The system will enable testing of candidate chemicals for their ability to influence differentiation of ESCMs and provide a platform for conducting chemical genomic studies of the differentiation process. We will develop an instrument that will help researchers produce heart cells from embryonic stem cells. Heart cells produced in this manner can potentially be used to treat heart disease. [unreadable] [unreadable] [unreadable]